Unmarried women in particular had been one of Democrats' most reliable bases. Some cited a lack of progress on fixing the economy; others had concerns over abortion rights in the healthcare law.

There are some signs that Democrats who raised abortion on the campaign trail fared better with women voters. In Colorado, Democratic Sen. Michael Bennet made a late play for female voters in part by attacking his opponent's antiabortion stance as extreme. Meanwhile, outside groups suggested that Republican Ken Buck, a former district attorney, had not aggressively prosecuted a rape case.

Bennet pulled 56% of the women's vote, helping him eke out a 1-percentage-point win.

Democratic women's groups are determined to regain the margins they lost this year. Executives at Emily's List, which backs candidates who support abortion rights, are already sifting through polling and research to formulate a plan to get more female voters in 2012.

"The one thing Democratic women said they needed was clearer info about candidates, something we intend to do more of — and earlier," said President Stephanie Schriock. "And we've got to break through on the economy. In this country, at this time, you can't take any group for granted."